The present invention is directed to a radioactive waste disposal system and more specifically to a method and apparatus for shredding and compacting radioactive waste material having a high percentage of plastic material of low specific, activity with predetermined amounts of radioactive ion exchange resin beads and subsequently heating and extruding the waste material into a sealable container without the addition of non-radioactive polymeric material.
Two different types of waste disposal systems are generally required for radioactive waste material having low specific activity and waste material which has a higher level of radioactivity. The waste material having a low specific activity, hereinafter referred to as LSA material, usually consists of packaging materials, protective material and the like which contain a high percentage of plastic material. In Applicant's prior U.S. Pat. No. 4,462,310, granted Jul. 31, 1984, the LSA material was compacted in a barrel or drum by means of a compacting device which was inserted in the barrel. The packing device included a base member having a peripheral configuration complementary t the cross-sectional configuration of the barrel, a plurality of threaded rods secured in spaced locations about the periphery of the base member and adapted to extend upwardly into proximity to the open end of the barrel, a supporting band secured to the ends of the rods opposite the base member, at least one intermediate plate having a peripheral configuration substantially the same as the base member and adapted to be disposed between the rods parallel to the base member and locking means secured to the intermediate plate and disposed in engagement with the threaded rods to allow movement of the intermediate plate toward the base member while preventing movement of the plate in the opposite direction. Thus after the insertion of a predetermined amount of compactable LSA material into the drum an intermediate plate would be inserted into the drum and pressed downwardly to compact the material and hold it in compacted condition while additional compactable material was added to the barrel. When the barrel was completely filled with compactable material a cover was secured to the drum and the drum could be disposed of in accordance with accepted procedures. Other radioactive waste material having a higher level of radioactivity could not be disposed of by such a method and other more complicated and expensive methods were required to dispose such radioactive material.
One system of disposing of such highly radioactive material, such as ion exchange resin bead wastes, is disclosed in the Gay et al, U.S. Pat No. 4,559,170, granted Dec. 17, 1985. According to this system the water present in the ion exchange resin bead waste is removed by heating the resin waste to a temperature sufficient to vaporize the water on the surface of the resin beads and to remove the water inside the ion exchange resin beads but insufficient to oxidize and combust the ion exchange resin bead waste. A dry flowable radioactive solid product is thereby produced which may be readily disposed of by conventional means such as storage, burial or incorporation into a solid matrix. Because of the makeup of the ion exchange resin beads and certain polymeric matrices used in monolithic storage, a polymeric matrix was used in order to incorporate large quantities of dry ion exchange resin beads into the monolith resulting from the polymerization of the matrix forming co-monomers.
The Bustard et al, U.S. Pat. No. 4,230,597, granted Oct. 28, 1980, also discloses a system for converting radioactive waste materials into solid form by mixing the radioactive waste with a novel polymeric formulation which when solidified forms a solid, substantially rigid matrix that contains and entraps the radioactive waste. The polymeric formulation comprises, in certain significant proportions by weight, urea-formaldehyde, methylated urea-formaldehyde, urea and a plasticizer. The radioactive waste in the form of a liquid or slurry is mixed with the polymeric formulation and the mixture is then treated with an acetic catalysing agent such as sulfuric acid. This mixture is then passed to a disposable container so that upon solidification of the radioactive waste entrapped within the matrix formed by the polymeric formulation, the radioactive waste may be safely and effectively stored at a disposal site.
Similar systems for disposing of radioactive waste are disclosed in the Gablin et al, U.S. Pat. No. 4,168,243, granted Sept. 18, 1979, and the Stock et al, U.S. Pat. No. 3,940,628, granted Feb. 24, 1976. The systems disclosed in these patents and the foregoing patents directed to the solidification of radioactive waste material all require the addition of a solidifying matrix such as a cement, a polymer matrix or the like. Thus the amount of radioactive waste material which can be disposed of in a single container is restricted by the amount of matrix necessary to solidify or encapsulate the waste material and the cost of the system is usually increased due to the necessity of adding an extraneous solidifying agent.